1. Field of the Invention
The present invention relates to an art to detect a posture of a medium such as a recording medium on which a recording apparatus records.
2. Description of the Related Art
An ordinary recording apparatus includes a recording head having a recording element and records an image on a recording medium by forming a large number of pixels on the recording medium by the recording element of the recording head while moving the recording head relatively to the recording medium. When, at the time of the image recording by the recording head, the recording medium is tilted in its plane from a posture that it should take, the image formed on the recording medium is tilted. Generally, this in-plane tilt of the recording medium is very small and cannot be easily detected by such a method as to detect a position of an edge of the recording medium by a sensor or the like provided in the recording apparatus. Therefore, the present inventors are considering providing, on a recording medium, detection target parts for enabling the detection of a tilt from a proper posture.
Japanese Patent Application Laid-open No. H09-15766 discloses an example where detection target parts detected by a detecting mechanism provided in a recording apparatus are provided on a recording medium. Concretely, disclosed is a lenticular sheet for stereoscopic image having: a lenticular lens including a plurality of convex lenses in a substantially columnar shape; and am image recording layer stacked on a flat surface, of the lenticular lens, opposite the convex lenses. On the flat surface, of the lenticular lens, opposite the convex lens part, a plurality of ribs corresponding to a plurality of pixel arrangement regions in the image recording layer are provided at equal intervals in a width direction of the convex lens part perpendicular to an axial direction of the convex lens part (generatrix direction), and these ribs project from the image recording layer. The recording apparatus has a carriage moving in the width direction of the convex lens part and an ink-jet head mounted on the carriage, and on the carriage, a sheet pitch sensor detecting the aforesaid ribs of the lenticular sheet is provided. The sheet pitch sensor detects the ribs of the lenticular sheet while moving with the carriage, to find positions of the pixel arrangement regions of the image recording layer, so that the ink jet head can accurately form an image.
The above-described lenticular sheet is provided with the ribs arranged at equal intervals in the width direction of the convex lens part. However, it is not possible to detect the tilt of the sheet only by detecting such ribs arranged in one direction by the sensor provided in the recording apparatus. Specifically, when the lenticular sheet is in such a posture that an arrangement direction of the ribs is parallel to the width direction of the convex lens part, it is detected that the ribs are arranged at equal intervals. On the other hand, when the lenticular sheet is tilted in its plane from the above posture by a certain angle, the ribs are also detected at equal intervals, and therefore, the above-described structure does not enable the detection of the tilt of the sheet.